1. Field of the Invention
The present invention relates to a power supply apparatus, and in particular, to an improved power supply apparatus for controlling electrical elements of a vehicle which apparatus is used for a vehicle using 12 volts as well as a vehicle using 24 volts.
2. Description of the Conventional Art
Generally, when parking a vehicle, the vehicle is moved in the backward direction.
When moving a vehicle in the backward direction, a transmission gear is positioned at a Rear position, and then a driver checks whether there is an obstacle behind the vehicle by turning his/her head to the backward direction using a rear mirror and a room mirror.
However, behind the vehicle and below a rear bumper of the vehicle, there is a non-checkable area where it is impossible to check by turning his/her head and using the rear mirror and the room mirror. If there is an obstacle in this area, the vehicle may collide with the obstacle when the vehicle is moved in the backward direction.
In order to overcome the above-described problem, a vehicle is provided with an ultrasonic sensor which is capable of sensing an obstacle placed or positioned just behind the rear portion of the vehicle. Therefore, when the vehicle is moved toward the obstacle, an alarm is issued when there is a predetermined distance between the vehicle and the sensor.
FIG. 1 illustrates a circuit diagram illustrating a conventional backward movement control apparatus. As shown therein, the conventional backward movement control apparatus includes a central processing unit (CPU) 1 for controlling an alarm when a vehicle is moved in the backward direction, an ultrasonic wave oscillator 2 for oscillating ultrasonic waves in accordance with a control of the central processing unit 1, a sensor driving unit 3 for amplifying an output signal from the ultrasonic wave oscillator 2, an ultrasonic wave sensor unit 4 for generating an ultrasonic wave in accordance with an output signal from the sensor driving unit 3 and detecting whether there is an obstacle behind the vehicle using a reflected ultrasonic wave, a wave shaping unit 5 for shaping an output signal from the ultrasonic sensor unit 4, an amplifier 6 for amplifying an output signal from the wave shaping unit 5, a comparator 7 for comparing the output signal from the amplifier 6 with a previously set reference voltage, detecting an obstacle, and inputting the detected result into the central processing unit 1, and an output interface unit 8 for driving the alarming unit 9 in accordance with a control of the central processing unit 1 and generating an alarm. Here, a power (preferably, 5 volts) is supplied to the central processing unit 1 through a power supply unit 20.
FIG. 2 illustrates a detailed circuit diagram of the power supply unit 20. A voltage of 12 volts is applied to a regulator 30 through a diode D10 and condensers C10 and C11 and then is transformed to a voltage of 5 volts. Thereafter, the voltage of 5 volts is supplied to the central processing unit 1. In the drawings, reference numerals C12 through C14 denote condensers, and R10 denotes a resistor.
In the thusly constituted conventional backward movement control apparatus, a voltage of 5 volts is applied to the central processing unit 1 through the power input unit 20. In this state, when a driver sets a transmission gear lever in the Rear mode in order to drive the vehicle in the backward direction, a backward movement signal is generated and inputted into the central processing unit 1.
Therefore, the central processing unit 1 judges the backward movement of the vehicle, controls the ultrasonic wave oscillator 2, thus oscillating ultrasonic waves.
The ultrasonic waves oscillated by the ultrasonic wave oscillator 2 are inputted into the sensor driving unit 3 and are amplified to a predetermined level and are inputted into the ultrasonic wave sensor unit 4 for driving the same.
Therefore, the ultrasonic wave sensor 4 generates ultrasonic waves and receives the reflected ultrasonic waves.
Since noises are mixed in the signals from the ultrasonic sensor unit 4, the ultrasonic waves are shaped by the wave shaping unit 5, thus filtering noises. Thereafter, the signals are amplified by the amplifier 6 and are inputted into the comparator 7. The thusly inputted signals are compared with a previously set reference voltage, and a result of the comparison is inputted into the central processing unit 1.
Thereafter, the central processing unit 1 judges whether there is an obstacle behind the vehicle based on the output signal from the comparator 7. As a result of the judgement, when an obstacle is judged to be within a predetermined range from the rear side of the vehicle, the central processing unit 1 outputs an alarm control signal, and the thusly outputted alarm control signal is inputted into the alarm unit 9 through the interface unit 8, whereby the alarming unit 9 alarms that there is an obstacle behind the vehicle.
Here, the comparator 7 judges the distances between the rear side of the vehicle and the obstacle by the distance of 110 cm, 80 cm, and 50 cm. Therefore, the alarming unit 9 generates three alarms in accordance with a control of the central processing unit 1.
However, in the conventional backward movement control apparatus for a vehicle, since the power circuit unit is provided with a power input unit for only 12 volts, it is impossible to use the backward movement control apparatus for 24 voltage units of a vehicle such as a bus, truck, or mini truck.